It's on the LM358/324 data sheet.

Try a current sink between the output and negative supply. A BC547, collector to output, emitter to negative and the base to +10V via a 1M resistor.
EDIT: Here's the schmatic.
I'll probably get some criticism for posting this, because it relies on the transistor's h
FE which isn't well controlled, but that doesn't matter. It just needs to pass enough current, to keep the op-amp's output near the negative rail.
